const fs = require("fs");
const path = require("path");

/*
 * Parses a string or buffer into an object
 * @param {(string|Buffer)} src - source to be parsed
 * @returns {Object} keys and values from src
*/
function parse(src) {
    const obj = {};

    // convert Buffers before splitting into lines and processing
    src
        .toString()
        .split("\n")
        .forEach(line => {
            // matching "KEY' and 'VAL' in 'KEY=VAL'
            const keyValueArr = line.match(/^\s*([\w\.\-]+)\s*=\s*(.*)?\s*$/);
            // matched?
            if (keyValueArr !== null) {
                const key = keyValueArr[1];

                // default undefined or missing values to empty string
                let value = keyValueArr[2] || "";

                /* eslint-disable */
                // expand newlines in quoted values
                const len = value ? value.length : 0;
                if (
                    len > 0 &&
                    value.charAt(0) === '"' &&
                    value.charAt(len - 1) === '"'
                ) {
                    value = value.replace(/\\n/gm, "\n");
                }
                /* eslint-disable */

                // remove any surrounding quotes and extra spaces
                value = value.replace(/(^['"]|['"]$)/g, "").trim();

                obj[key] = value;
            }
        });

    return obj;
}

/*
 * Main entry point into dotenv. Allows configuration before loading .env
 * @param {Object} options - options for parsing .env file
 * @param {string} [options.path=.env] - path to .env file
 * @param {string} [options.encoding=utf8] - encoding of .env file
 * @returns {Object} parsed object or error
*/
function config(options) {
    let dotenvPath = path.resolve(process.cwd(), ".env");
    let encoding = "utf8";

    if (options) {
        if (options.path) {
            dotenvPath = options.path;
        }
        if (options.encoding) {
            encoding = options.encoding;
        }
    }

    try {
        // specifying an encoding returns a string instead of a buffer
        const parsed = parse(fs.readFileSync(dotenvPath, { encoding }));

        Object.keys(parsed).forEach(key => {
            process.env[key] = parsed[key];
        });

        return { parsed };
    } catch (e) {
        return { error: e };
    }
}

module.exports.config = config;
module.exports.load = config;
module.exports.parse = parse;
